Energy has traditionally been produced from petroleum and other fossil fuels, but in recent years, concerns have emerged regarding the depletion of fossil fuels, emissions of greenhouse gases such as carbon dioxide from the use of fossil fuels, and rising fuel costs.
Sunlight, which is renewable and involves no fuel costs, has been gathering attention as a new energy source.
There are a number of different solar heat collecting apparatuses that use sunlight as their energy source, which can be differentiated by the system of sunlight collection (See Patent Literature 1). Among these, for example, are the parabolic trough type and the linear Fresnel type heat collectors, as well as the tower type heat collector.
The parabolic trough heat type collector consists of a trough-shaped parabolic mirror used to reflect sunlight and collect it in the receiver to collect solar heat.
The linear Fresnel type heat collector consists of plural reflecting mirrors installed on plural parallel reflection lines laid out in the north-south direction, and a receiver installed over the mirrors in a north-south oriented reception line to collect sunlight reflected from the mirrors and thereby collect solar heat.
The tower type heat collector uses plural reflecting mirrors installed around a tower to collect sunlight and thereby collect solar heat in the receiver on the tower.